// Copyright 2015-2020 Parity Technologies (UK) Ltd.
// This file is part of Parity Ethereum.

// Parity Ethereum is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// Parity Ethereum is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with Parity Ethereum.  If not, see <http://www.gnu.org/licenses/>.

//! Solidity type-name parsing
use lunarity_lexer::{Lexer, Token};
use crate::error::*;
use std::{fmt, result};

#[derive(Debug, Clone, PartialEq)]
pub enum Type {
	Address,
	Uint,
	Int,
	String,
	Bool,
	Bytes,
	Byte(u8),
	Custom(String),
	Array {
		length: Option<u64>,
		inner: Box<Type>
	}
}

impl From<Type> for String {
	fn from(field_type: Type) -> String {
		match field_type {
			Type::Address => "address".into(),
			Type::Uint => "uint".into(),
			Type::Int => "int".into(),
			Type::String => "string".into(),
			Type::Bool => "bool".into(),
			Type::Bytes => "bytes".into(),
			Type::Byte(len) => format!("bytes{}", len),
			Type::Custom(custom) => custom,
			Type::Array {
				inner,
				length
			} => {
				let inner: String = (*inner).into();
				match length {
					None => format!("{}[]", inner),
					Some(length) => format!("{}[{}]", inner, length)
				}
			}
		}
	}
}

impl fmt::Display for Type {
	fn fmt(&self, f: &mut fmt::Formatter) -> result::Result<(), fmt::Error> {
		let item: String = self.clone().into();
		write!(f, "{}", item)
	}
}


/// the type string is being validated before it's parsed.
pub fn parse_type(field_type: &str) -> Result<Type> {
	#[derive(PartialEq)]
	enum State { Open, Close }

	let mut lexer = Lexer::new(field_type);
	let mut token = None;
	let mut state = State::Close;
	let mut array_depth = 0;
	let mut current_array_length: Option<u64> = None;

	while lexer.token != Token::EndOfProgram {
		let type_ = match lexer.token {
			Token::Identifier => Type::Custom(lexer.slice().to_owned()),
			Token::TypeByte => Type::Byte(lexer.extras.0),
			Token::TypeBytes => Type::Bytes,
			Token::TypeBool => Type::Bool,
			Token::TypeUint => Type::Uint,
			Token::TypeInt => Type::Int,
			Token::TypeString => Type::String,
			Token::TypeAddress => Type::Address,
			Token::LiteralInteger => {
				let length = lexer.slice();
				current_array_length = Some(length
					.parse()
					.map_err(|_|
						ErrorKind::InvalidArraySize(length.into())
					)?
				);
				lexer.advance();
				continue;
			}
			Token::BracketOpen if token.is_some() && state == State::Close => {
				state = State::Open;
				lexer.advance();
				continue;
			}
			Token::BracketClose if array_depth < 10 => {
				if state == State::Open && token.is_some() {
					let length = current_array_length.take();
					state = State::Close;
					token = Some(Type::Array {
						inner: Box::new(token.expect("if statement checks for some; qed")),
						length,
					});
					lexer.advance();
					array_depth += 1;
					continue;
				} else {
					return Err(ErrorKind::UnexpectedToken(lexer.slice().to_owned(), field_type.to_owned()))?;
				}
			}
			Token::BracketClose if array_depth == 10 => {
				return Err(ErrorKind::UnsupportedArrayDepth)?;
			}
			_ => return Err(ErrorKind::UnexpectedToken(lexer.slice().to_owned(), field_type.to_owned()))?
		};

		token = Some(type_);
		lexer.advance();
	}

	Ok(token.ok_or(ErrorKind::NonExistentType)?)
}

#[cfg(test)]
mod tests {
	use super::*;

	#[test]
	fn test_parser() {
		let source = "byte[][][7][][][][][][][]";
		parse_type(source).unwrap();
	}

	#[test]
	fn test_nested_array() {
		let source = "byte[][][7][][][][][][][][]";
		assert_eq!(parse_type(source).is_err(), true);
	}

	#[test]
	fn test_malformed_array_type() {
		let source = "byte[7[]uint][]";
		assert_eq!(parse_type(source).is_err(), true)
	}
}
